Turbine blades are the primary elements of wind turbines for converting wind energy into electrical energy. The blades have the cross-sectional profile of an airfoil such that, during operation, air flows over the blade producing a pressure difference between the sides. Consequently, a lift force, which is directed from a pressure side towards a suction side, acts on the blade. The lift force generates torque on the main rotor shaft, which is geared to a generator for producing electricity.
The turbine blades typically consist of a suction side shell and a pressure side shell that are bonded together at bond lines along the trailing and leading edges of the blade. An internal shear web extends between the pressure and suction side shell members and is bonded to spar caps affixed to the inner faces of the shell members. With typical blade constructions, a rigid flange is used to achieve a desired bond width for bond paste applied between the spar caps and transverse ends of the shear web. This configuration, however, often results in the use of excess bond paste to achieve the bond width. The excess paste contributes unnecessary weight to the blade and can break off and result in blade “rattling” during operation of the wind turbine (a not uncommon complaint from wind turbine owners/operators). Also, air voids and unpredictable squeeze-out of the bond paste in the typical construction can result in areas of decreased bond strength, which is particularly problematic in sections of the blade where repair is not possible from within the blade.
Accordingly, the industry would benefit from an improved bond configuration between the shear web and spar caps that addresses one or more of the deficiencies of certain conventional configurations.